/Engine/Source/Runtime/Experimental/Chaos/Public/Chaos/Levelset.h
Estimate the volume bounded by the zero'th isocontour of the level set. #BGTODO - We can generate a more accurate pre-calculated volume during generation as this method still under estimates the actual volume of the surface.
[FReal](API\Runtime\ChaosCore\Chaos\FReal) ApproximateNegativeMaterial() const